Exterior elevator systems are commonly used in the construction of new buildings and on elevated smoke stacks for maintenance purposes.
In FIG. 1 is set forth an illustration of a common prior art approach for installing exterior elevator systems to a slanted wall (2-3 degrees) smoke stack. Typically, three mast sections 100 are mounted to the wall or side 110 of a smoke stack 120. The first three sections are mounted onto a base plate 102 and are plumbed and affixed to each other and then affixed to the wall 110. An elevator car 130 is mounted to the three mounted rail sections 100 by taking the bottom of the elevator 130 off, lifting it up and over the three installed rail mast sections by means of a crane or cherry picker (not shown) and then dropped over the rail and lowered onto the base plate. The elevator car 130 is then reassembled and a temporary platform 140 is built on top of the car 130 and electrical connections are attached thereto. The remaining rail mast sections generally designated as stack 150 are then lifted into position by means of a pully or whip system 160 having a wire rope 162. After installing nine to ten rail mast sections, the car 130 can be used to provide the hoisting power.
One major disadvantage of the approach shown in FIG. 1 is the time required to erect the rail mast sections. Typically only one section is hoisted to the temporary platform. The elevator car is then activated to travel upwardly to the upper end of the assembled sections. That carried section is then installed to the lower sections and to the wall. The car then travels down the assembled rail sections to receive and to carry the next rail mast section up. As it travels down it hoists the next section. Significant time elapses for traveling up and down the smoke stack. Hence, back charges or penalties incurred for installation delays (not only for the installation of the elevator system, but also for other crafts) may be significant. Because of the slow installation time, the structure poses a hazard as airplane strobe lights and lightening rods are not rapidly installed. Contraiwise, the present invention provides a method of installation which significantly speeds up construction time.
Another major disadvantage of the approach shown in FIG. 1 resides in the use of a temporary platform 140 which is constructed on top of the elevator car. Lifting rail mast sections to the temporary platform may result in an unsafe condition such as dropping tools or materials. Indeed, receiving the rail mast section on the platform and then installing it to the structure incurs a number of possible hazardous situations such as falling from the platform. On the other hand, the present invention does not require the construction of a temporary platform, nor the necessity of having personnel work at high levels.
Another disadvantage of the prior art approach is the lack of straightness of the finally installed rail sections vertically along the smoke stack which may result in crooked or ill-fitting joints between the sections. Such crooked joints cause a clicking noise as the elevator passes over, a rougher ride, and the possibility that the overspeed safety devices may not properly set. In the present invention, the creation of ill-fitted joints are substantially minimized since the force of gravity aligns along assembled rail mast sections. As another feature, the present invention does not cause weakening of the walkway supports as found in the prior approach where the hole in the walkway must be dimensionally fitted to receive the elevator system.
No prior approach utilizing the method of the present invention to erect rail mast sections to the wall of a structure is known to exist. The present invention offers an approach that is low in cost, safe, and one that can be easily installed. The practice of the present invention is not limited to use on smoke stacks, but is applicable to any elevated structure.